Top closure for a rectangular box

Abstract

The top closure of the present invention comprises a flexible sheet member sized to fit in covering relation over a top opening of a box. One edge of the sheet member is attached to the upper edge of one of the box walls. At least one track is positioned at one of the opposite ends of the box and an elongated shaft extends between the two opposite ends of the box. The tracks guide the shaft from an open position adjacent one edge of the box to a closed position adjacent the other upper edge of the box. The flexible sheet member is rolled around the shaft when the shaft is in its open position, and the sheet member unrolls from the shaft as the shaft rolls towards its closed position. When the shaft reaches its closed position, it engages a plurality of flaps which are mounted along the edge of the box. These flaps wrap around the shaft as the shaft rotates, and become attached to the shaft, thereby fastening the shaft to the sidewalls of the box with the tarpaulin in covering relationship over the opening. Reversal of the rotational direction of the shaft causes the flaps to unroll and detach from the shaft so that the shaft can roll back towards its open position, and thereby uncover the opening in the box. The shaft may be rotated either by an electrical motor or by a manual crank. The motor has a gear box which functions as a brake against rotation when the motor is deactuated.

What is claimed is: 
     
       1. A top closure for a rectangular box having a pair of opposite end walls and a pair of opposite side walls, said box having a top opening adjacent the upper edges of said end and side walls, said top closure comprising: a flexible sheet member having first and second opposite edges and being sized to fit in covering relation over said top opening;   anchor means attaching said first edge of said sheet member to one of said side walls adjacent said upper edge thereof;   at least one of said upper edges of said end walls being provided with track means, said track means being elongated and extending from one said box side wall to the other of said box side walls;   an elongated shaft spanning the distance between said upper edges of said end walls, said shaft having at least one end retentively engaged by said track means for movement from an open position wherein said shaft is adjacent said one box sidewall to a closed position wherein said shaft is adjacent said other box sidewall;   spring means interconnecting said box and said shaft for yieldably urging said shaft to said closed position;   said shaft being attached to said second edge of said sheet member with said sheet member being wound around said shaft when said shaft is in said open position, said shaft being capable of turning and unwinding said sheet member while moving from said open to said closed position;   power means connected to said shaft for rotating said shaft to wind and unwind said sheet member;   securing means connected adjacent said upper edge of said other side wall for retentively engaging said shaft when shaft is in said closed position.   
     
     
       2. A top closure according to claim 1 wherein said securing means comprising at least one flexible flap having a first end and a second end, said first end being attached to said other sidewall so as to hold said second end in a position which is in the path of said rotating shaft as said shaft moves from said open to said closed position, whereby said second end of said flap will wind around and become attached to said shaft during continued movement of said rotating shaft to said closed position. 
     
     
       3. A top closure according to claim 1 wherein said flexible flap has a normal position wherein said second end extends upwardly from said first end and protrudes upwardly above said upper edge of said other sidewall, said flap being made of resilient material which will yield and bend when engaged by said shaft so that said rotating shaft will cause said flap to wind around said shaft and become attached thereto. 
     
     
       4. A top closure according to claim 1 wherein said power means comprises an electric motor drivingly connected to said shaft for rotating said shaft. 
     
     
       5. A top closure according to claim 4 wherein brake means interconnect said motor and said shaft for preventing rotation of said shaft when said motor is deactuated. 
     
     
       6. A top closure according to claim 1 wherein said power means comprises a crank handle operatively connected to said shaft for permitting manual rotation of said shaft. 
     
     
       7. A top closure for a rectangular box having a pair of opposite end walls and a pair of opposite side walls, said box having a top opening adjacent the upper edges of said end and side walls, said top closure comprising: a flexible sheet member having first and second opposite edges and being sized to fit in covering relation over said top opening;   anchor means attaching said first edge of said sheet member to one of said side walls adjacent said upper edge thereof;   at least one of said upper edges of said end walls being provided with track means, each of said track means being elongated and extending from one said box side wall to the other of said box side walls;   an elongated shaft resting on said upper edges of said end walls, at least one end of said shaft retentively engaged by said track means for movement from an open position wherein said shaft is adjacent said one box sidewall to a closed position wherein said shaft is adjacent said other box sidewall;   said shaft being attached to said second edge of said sheet member with said sheet member being wound around said shaft when said shaft is in said open position, said shaft being capable of turning and unwinding said sheet member while moving from said open to said closed position;   securing means connected adjacent said upper edge of said other side wall for retentively engaging said shaft when shaft is in said closed position;   reversible power means connected to said shaft and being actuatable for rotating said shaft to wind and unwind said sheet member;   brake means connected to said power means for preventing the rotation of said shaft when said power means is deactuated.